Fluid sterilization apparatus

ABSTRACT

Apparatus for treating water or other fluid with radiant energy from an ultraviolet lamp includes a helical shaped input fluid flow guide or helical ramp disposed at or near one end an elongated annular chamber around the lamp. The guide or ramp serves to impart input spiral flow momentum to the fluid upon entry to the chamber. A corresponding output fluid flow guide or helical ramp may be disposed at or near the opposed end of the chamber to impart output spiral flow momentum to the fluid as it approaches discharge from the chamber. Spiral flow serves to extend the time that the fluid is exposed to ultraviolet light and thereby increases the probability that any microbiological contaminants present in the fluid will be killed. The use of helical shaped guides or ramps better serves to establish such a flow in circumstances where the available fluid pressure is relatively low.

FIELD OF THE INVENTION

This invention relates to fluid sterilization apparatus of the type fortreating potable water or other fluids with radiant energy from anultraviolet lamp.

BACKGROUND TO THE INVENTION

It is well known that the quality of potable water varies widely fromcity to city around the world. Indeed, the quality can varysignificantly from place to place within a given city. To address thisissue, numerous water treatment systems have been designed for domestichome use: A typical system may include a water filter for removingparticulates and organic contaminants from the water, an ultravioletlamp for irradiating the water with ultraviolet energy to killcontaminants in the water, a subsystem for operating and monitoring theoperation of said system, and structures for housing such components.Often, such systems are designed to sit on a countertop in the user'shome where they are connected to a public utility or other municipalwater supply. For example, see U.S. Pat. No. 5,698,091 (Kuennen et al.)granted on Dec. 16, 1997.

It is also well known that the quality of potable water carried on boardpassenger vehicles such as aircraft, trains and ships can varysignificantly: for example, see Weisel, Al “Dirty Water—Ourinvestigation into water on airplanes will make you think before yourdrink”, Travel & Leisure, December 1998, pages 139-142. In the case ofsuch vehicles, the quality of potable water will depend not only on thesource from whence the water came, but also on the integrity of on boardstorage tanks and supply lines where contamination may result frommicroorganism growth or biofilm buildup.

Accordingly, just as it is desirable to provide for the treatment ofpotable water in the home, it is desirable to provide for the treatmentof potable water carried on board vehicles. However, the workingenvironment to be found on board a vehicle may differ significantly fromthat to be found in the home. A water treatment system or componentsthereof that function reliably and well in the home may not function atall well in a mobile working environment.

As will now be described, the present invention focuses on one such areaof limitation. More particularly, it focuses on sterilization apparatusthat may be used in the treatment of water or other fluids with radiantenergy from an ultraviolet lamp.

As the prior art reveals, such apparatus commonly includes an outerhousing having first and second ends, a hollow cylindrical portionextending between such ends, and a coaxially aligned inner housing, thelatter of which is designed to hold an ultraviolet lamp. The housingsare sized to define an elongated annular region or chamber between thehousings. As fluid flows from an inlet at one end of the chamber to anoutlet at the opposed end, it is exposed to ultraviolet energy thatemits from the lamp into the annular chamber through a wall of the innerhousing which transmits ultraviolet light.

In such apparatus, the desirability of maintaining the fluid for anextended period of time within the field of view of the radiation iswell known. If microbiological contaminants are present, then theprobability of killing such contaminants will be enhanced. Consequently,various means have been devised to achieve this result.

For example, U.S. Pat. No. 4,008,045 (David Free) granted on Feb. 15,1977, describes an ultraviolet sterilizer that includes a diffuser platethrough which fluid in the an annular chamber must pass as it flows froman inlet at one end of the chamber to an outlet at the other. Thediffuser serves to impart turbulence and a spiral flow to the fluidthereby increasing the distance that a given control volume of fluidwill travel while flowing from the diffuser to the chamber outlet.

However, it has been found that the pressure drop or head loss thatoccurs across such diffusers is relatively high. This can bedisadvantageous if the fluid supply pressure is concurrently limited andit is desired to maintain a minimal water flow rate. More particularly,it may be observed that in a home use environment the input waterpressure from a public utility or municipal water source typically maybe of the order of 100 psig. If so, then the pressure drop across adiffuser in an ultraviolet sterilization chamber tends not to be anissue. In contrast, and although there may be some exceptions, thepressure produced by a water pump on a passenger aircraft may typicallybe only 45 psig or lower—sometimes as low as 20 psig. For a desiredwater flow rate through an ultraviolet sterilizer, such low pressuresmay preclude the use of a diffuser or, alternately, may preclude the useof other water treatment devices which themselves cause a pressure drop(e.g. a water filter) in the path of water flow.

As a further example, U.S. Pat. No. 4,141,686 (Lewis) granted on Feb.27, 1979, describes an ultraviolet sterilizer that includes a fin whichimparts turbulence to water as it flows into the annular chamber of thesterilizer. While it may be remarked that the pressure drop induced bythe fin described by Lewis is likely to be minimal, and while it mayalso be remarked that turbulence is desirable, it must also be remarkedthat Lewis' fin is not well adapted to induce a desirable spiral flow.Apart from turbulence, a significant volume of the water that enters theannular chamber may follow a relatively short path (sometimes referredto as a short circuit path) rather than a spiral path to the chamberoutlet. Thus, the water's exposure to ultraviolet radiation isundesirability limited.

As a more recent example, Kuennen et al., supra, describe a diverterplate and baffle arrangement that serves to impart a spiral flow withinthe annular chamber of an ultraviolet sterilizer. However, it is notedthat they specifically contemplate a high pressure home use environment,and it is anticipated that a significant pressure drop would occur,particularly across the baffle which may be compared with the diffuserof Free. The diverter plate and baffle arrangement is described in moredetail in U.S. Pat. No. 5,393,419 (Tiede et al who are part of Kuennenet al.) granted on Feb. 28, 1995.

Kuennen et al. also point out that other embodiments may by used toimpart a spiral flow to water passing through their annular chamber.They indicate that a spiral glass or polymeric (e.g. TEFLON®) tube maybe coiled about the ultraviolet lamp with a spiral pitch from the waterinlet end of the chamber to the water outlet end, and that such materialhas adequate ultraviolet transmissibility to achieve excellent killrates. However, even assuming that ultraviolet transmissibility isnormally adequate, there are disadvantages. Firstly, there would be arelatively high pressure drop across the coil by reason of the addedsurface area presented by the surfaces of the coil over the length ofthe coil. Secondly, it has to be recognized that sediment can build upon all surfaces over which water flows. In a case where a coil assuggested by Kuennen et al. is used, this would include not only thewall surfaces of the annular chamber, but also on the surfaces definingthe coil. Sediment build up on the walls of the coil could very wellimpair the transmissibility of coil material that otherwise mightdemonstrate adequate ultraviolet transmissibility.

Accordingly, a primary object of the present invention is to provide newand improved apparatus for treating water or other fluid with radiantenergy from an ultraviolet lamp in circumstances where the availablefluid pressure is relatively low.

SUMMARY OF THE INVENTION

In a broad aspect of the present invention, there is provided apparatusfor treating water or other fluid with radiant energy from anultraviolet lamp, such apparatus comprising an outer housing comprisingfirst and second ends and an elongated hollow cylindrical portionextending between the ends peripherally around a longitudinal axis ofthe cylindrical portion, and a hollow cylindrical inner housing forhousing the ultraviolet lamp. The inner housing is supported by the endsof the outer housing and extends coaxially within the cylindricalportion of the outer housing so as to define an elongated annularchamber between the housings. At least a substantial portion of thelength of the inner housing is formed from material, preferably quartz,which is sufficiently transmissible to permit ultraviolet energyradiating from the lamp to pass through the inner housing into thechamber and thereby irradiate fluid flowing through said chamber. Theapparatus further comprises a fluid inlet conduit extending through thefirst end of the outer housing from a fluid inlet port to the annularchamber, and a fluid outlet conduit extending through the second end ofthe outer housing from the annular chamber to a fluid outlet port. Thefluid inlet conduit serves to receive fluid from an external source andto direct such fluid to the annular chamber. Conversely, the fluidoutlet conduit serves to discharge fluid from the annular chamber.Further, the apparatus includes a helical shaped input fluid flow guideor helical ramp for imparting input spiral flow momentum to fluid uponentry to the annular chamber from the fluid inlet conduit. Preferably,it also includes a corresponding helical shaped output fluid flow guideor helical ramp for imparting output spiral flow momentum to fluidapproaching discharge from the chamber through the fluid outlet conduit.

The input fluid flow guide or ramp is disposed within the annularchamber and extends longitudinally therein from the first end of theouter housing for a relatively short distance. Conversely, the outputfluid flow guide or ramp, which is also disposed within the annularchamber but relatively far from the input flow guide or ramp, extendslongitudinally from the second end of the outer housing for a relativelyshort distance.

In contrast to diffusers, baffles, or helical shaped guides that extendcontinuously for substantially the full length of an annular chamber,all of which may offer relatively high resistance to fluid flow and maypresent other disadvantages, the helical shaped guides as specifiedherein offer relatively low resistance. Yet, it has been found that theycan serve to impart a significant and desirable spiral flow momentum tothe fluid.

Preferably, a helical guide or ramp will have an inner radiussubstantially corresponding to an outer radius of the inner housing andan outer radius substantially corresponding to an inner radius of theouter housing. Otherwise some fluid may flow around the sides of theguide or ramp with little or no spiral momentum.

The foregoing and other features of the present invention will now bedescribed with reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially exploded perspective view of a water treatmentsystem that incorporates apparatus in accordance with the presentinvention for treating fluid with radiant energy from an ultravioletsource.

FIG. 2 is a top view of a portion of the system shown in FIG. 1 when inan assembled condition, the apparatus which incorporates the presentinvention lying generally to the left.

FIG. 3 is a sectional elevation view of a portion of the system shown inFIG. 1 when in an assembled condition, the apparatus which incorporatesthe present invention lying generally to the left.

FIG. 4 is a sectional view from below of a portion of the system shownin FIG. 1 when in an assembled condition, the apparatus whichincorporates the present invention lying generally to the left.

FIG. 5 is an enlarged cut-a-way view of the upper left corner of FIG. 3.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

FIG. 1 illustrates a preferred embodiment of the present invention whenconfigured to integrate with and form part of a potable water treatmentsystem that includes not only apparatus generally designated 5 fortreating water with radiant energy from an ultraviolet lamp, but alsoapparatus generally designated 200 for filtering such water before it isexposed to ultraviolet light. Further, the system as shown includes ahousing assembly generally designated 300 to hold electrical andelectronic components and circuitry for operating and monitoring theoperation of the system. As well, the system includes a cover 400 whichnormally overlies lamp apparatus 5, filter apparatus 200, and housingassembly 300.

It is to be understood that cover 400 and generally that part of thesystem appearing within broken border 500, including filter apparatus200 and housing assembly 300, is not considered to be part of thepresent invention. They are illustrated in the drawings only to betterexplain the rationale for the particular configuration of lampapparatuss which appears in the drawings. More particularly, the overallsystem is one which is designed and configured for operation on board anaircraft under conditions of relatively low water pressure, and thepreferred embodiment described herein is designed as an integral part ofthat system. However, conditions of low pressure may be found elsewhere.As well, although water filtration is often desirable, it will beappreciated that the present invention does not require such filtration.Accordingly, in other applications, lamp apparatus 5 may assumediffering configurations.

Lamp apparatus 5 comprises an outer housing which includes first andsecond ends or end caps 10, 20, and an elongated cylindrical portion 35that extends between such ends and peripherally around axis 36, thelatter of which aligns with the cylindrical or longitudinal axis ofcylindrical portion 35. During assembly, ends 10, 20 are slidingreceived by cylindrical portion 35 and then glued in place as shown inFIG. 2. Further lamp apparatus 5 comprises a hollow cylindrical sheathor inner housing 40.

Inner housing 40 is supported by housing ends 10, 20 by means of sheathretainers 11, 21 which are threadingly engageable with the main body ofthe ends, and which are considered to form part of such ends. Innerhousing 40 extends coaxially within cylindrical portion 35 so as todefine an elongated annular chamber 50 between the inner and outerhousings.

An ultraviolet lamp 90 is housed by inner housing 40, and extendslongitudinally therein between ceramic end caps 91, 92 (see FIG. 3).When in place, lamp 90 is secured at opposed ends by lamp retainingplugs 19, 29 which are threadingly engageable with the main body of ends10, 20 respectively, and which are considered to form part of such ends.Power input to the lamp is provided through wires 95 which may receivepower from any appropriate power source and power supply circuitry.

It will be noted that plugs 19, 29 are not solid plugs; they are ringshaped to leave an air opening through their centers. Likewise, it willbe noted that there is an annular air space between sheath retainers 11,21 and end caps 91, 92. Also, there is an annular air space between caps91, 92 and the inner wall of housing 40. All of such air spaces andopenings serve to facilitate the air cooling of the lamp 90 when it isin place and in operation.

Lamp 90 is sealed from annular chamber 50 by means of elastomeric “O”rings 18, 28 which are respectively associated with ends 10, 20. As bestseen in FIG. 5, ring 28 is normally compressed between housing 40, aninner flange end 20, and retainer 21, thereby forming a water tightseal. Although not depicted in detail, ring 18 in cooperation withretainer 11 forms a seal at end 10 in the same manner.

The main bodies of ends 10, 20 and retainers 11, 19, 21 and 29 may allbe fabricated from polyvinyl chloride (PVC) plastic. Cylindrical portion35 is preferably formed from chlorinated PVC which has about 50% morestrength as well as fire retardant properties.

Inner housing 40 is formed from a material sufficiently transmissible topermit ultraviolet energy radiating from lamp 90 to pass through housing40 and flood chamber 50 with such energy. Then, as water flows throughchamber 50 in the manner described below, it is irradiated with theultraviolet energy. Preferably the material forming inner housing 40 isa high purity quartz material. As is well known, such material transmitultraviolet energy very well.

As best seen in FIGS. 1, 3 and 4, a water inlet conduit 13 extendsthrough end 10 from a water inlet port 12 to chamber 50. As shown inFIG. 4, conduit 13 includes an annular race 14 (which race is ofprogressively decreasing depth). Inlet port 12 appears in a water inletfitting 15 which forms part of end 10 and which is normally threadinglyengaged with arm 16 of end 10. More specifically, fitting 15 as shown isthe female portion of a quick connect coupling that enables theapparatus 5 to be releasably connected in water flow communication withan external source of water. In the embodiment shown, the immediatesource of external water received via fitting 15 is the output fromfilter apparatus 200 through fitting 226. It necessarily follows thatfitting 226 is a male counterpart of female fitting 15.

As best seen in FIG. 3 and also FIG. 5, a water outlet conduit 23extends through end 20 from chamber 50 to a water outlet port 24. Outletport 24 appears in a water outlet fitting 26 which forms part of end 20and which is normally threadingly engaged with the circular body portion25 of end 20. More specifically, fitting 26 as shown is the male portionof a quick connect coupling that enables the apparatus to be releasablyconnected in water flow communication with a water line (not shown)leading to a tap (also not shown) from which a user may draw water. Ofcourse, it will be understood that the water line should begin with acorresponding female fitting (not shown). In practice, it will likely beconvenient for fitting 26 to be the same kind of fitting as fitting 226,and for the fitting at the beginning of the water line leading to thetap to be the same kind of fitting as fitting 15.

Referring now to FIGS. 1 and 3, it will be seen that the apparatusfurther includes a helical shaped input fluid flow guide or ramp 60disposed within chamber 50 and extending longitudinally therein from end10 for a relatively short distance. Further, it will be seen that theapparatus includes a helical shaped output fluid flow guide or ramp 70also disposed within chamber 50 and extending longitudinally thereinfrom end 20 for a relatively short distance. These features are at thefocus of the present invention.

Each ramp extends for about one helical revolution. In relation to theoverall length of cylindrical portion 35, it will be noted that thelongitudinal extension of ramps 60, 70 as determined by their helicalpitch is relatively short, and that there is a substantial distancebetween the ramps. Thus, a substantial part of the field of view thatultraviolet lamp 90 has of chamber 50 is unimpeded by the ramps.

As best seen in FIG. 1, ramp 70 is secured by a pin 71 to end 20.Although not shown, ramp 60 is likewise secured to end 10.

Just as end portion 10 includes a transversely extending arm 16, it willbe observed that end 20 includes a transversely extending arm 30. Thesearms are not essential to the present invention and both ends 10, 20could be reconfigured to have a more compact cylindrical cap form.However, the ends are illustrated with the present embodiment becausethey serve to integrate apparatus 5 with the overall water treatmentsystem illustrated in FIG. 1.

Briefly, end 10 of lamp apparatus 5 connects via fitting 15 in directwater flow communication via fitting 226 with the output ofcorresponding end 220 of filter apparatus 200. Concurrently, end 20 oflamp apparatus 5 mechanically connects with opposite end 210 of filterapparatus 200. With respect to the latter connection, stub 31 at thedistal end of arm 30 (see FIG. 1) is slidingly received by acorresponding recess (not shown) in end 210 of filter apparatus 200. End210 of filter apparatus 200 includes a water inlet fitting 215.Preferably, this fitting is essentially the same type of male fitting asfittings 26 and 226.

When connections are made in the manner indicated in FIGS. 2 to 4, thenet result is that arms 16, 30 of lamp apparatus 5 serve to providemechanical support for filter apparatus 200. In the system shown in FIG.1, this support is enhanced by housing assembly 300 which not onlyserves to cradle and support lamp apparatus 5 and filter apparatus 200when they are connected, but also provides a structure to which arms 16and 30 of lamp apparatus 5 may be bolted by means of bolts such as bolts301. Structural integrity is further enhanced by cover 400, preferablymade from fire retardant plastic. Cover 400 includes a curvate end and aflat upper plate portion which extends away from the curvate end. Thecurvate end abuts and conforms with the curvature of cylindrical portion35 and is normally bolted to each of three support leaves (see FIG. 1)that project upwardly and outwardly from the base of housing assembly300. The flat upper plate portion of cover 400 extends over and isbolted to the top of housing assembly 300, and marginally extends overfilter apparatus 200. The result is a well integrated structure which isresistant to shock and vibration conditions that may be encountered onboard an aircraft.

In order to facilitate the replacement of water filter 290, cover 400does not wrap around cylindrical portion 235 of filter apparatus 200 inthe manner of cylindrical portion 35 of lamp apparatus 5. If filterreplacement is required, it is merely necessary to release theengagement between fitting 226 and fitting 15 and pull the entire filterapparatus laterally away from housing assembly 300. Concurrently, end210 of filter apparatus 200 slides out of engagement with stub 31 oflamp apparatus 5. Then, filter replacement is made possible by removingend 220 of filter apparatus 200, which end is normally threadinglyengaged with cylindrical portion 235. (Opposed end 210 is normallysecured by glue.)

The replacement of lamp 90 is achieved by unthreading retainers 19 and11 from end 10 of lamp apparatus 5, removing the lamp longitudinallyalong axis 36, disconnecting wires 95, and then installing a new lamp.

In operation, pressurized potable water having entered the annularregion of filter apparatus 200 through fitting 215, and been filtered byhollow core filter 290, then enters the lamp apparatus 5 at end 10through inlet port 12. The input flow first follows water inlet conduit13 which leads to and includes annular race 14, from which the flowexits into the path defined by helical ramp 60. Ramp 60 directs theincoming flow in a clockwise spiral path and thereby imparts angular orinput spiral flow momentum to the water. As the flow leaves ramp 60 inchamber 50 and moves toward end 20, it thus begins to traverse thelength of the chamber in a spiral path as indicated by arrows 99 in FIG.3.

Of course, the input spiral flow is desirable because it serves toincrease the length of time that water will be exposed to ultravioletlight from lamp 90. It may also be noted that trailing edge 61 of ramp60 (see FIG. 1) may induce a degree of desirable turbulence in the flow.More particularly, in a related test where colored dye was injected intoa water flow. there was visible flow separation or eddying turbulence aswater passed over a trailing edge similar to edge 61. However, it ispresently not possible to quantify the degree of turbulence or whatconditions should prevail to ensure at least some turbulence.

While the initial spiral flow imparted by ramp 60 is desirable in and ofitself, and while ramp 60 will serve a primary object of the presentinvention with or without the presence of ramp 70, the combined presenceof ramp 70 serves the primary object to an enhanced degree. Moreparticularly, as a water flow approaches end 20 and ultimate dischargefrom chamber 50, ramp 70 constrains the flow to move in a spiral path.Perhaps akin to a whirlpool effect, this constraint serves to induce aspiral motion and impart an output spiral flow momentum to the waterbefore it reaches ramp 70.

Along ramp 70, the output flow is directed in a continuing clockwisespiral path to outlet conduit 23. The water, now having been treatedwith ultraviolet radiation from lamp 90, then leaves the apparatus atend 20 through outlet port 24 and is available for drinking or otheruse.

In a test apparatus wherein a chamber 50 was defined between an innerhousing 40 having an outside diameter of about 1 inch and a cylindricalportion 35 having an inside diameter of about 2.5 inches, and againusing colored dye for the purpose of observation, it was observed thatabout 8 to 10 fluid spiral revolutions occurred between a ramp 60 and aramp 70, each having a helical pitch of about 3 revolutions per inch.The overall chamber length was about 8.5 inches. This observation wasmade with a flow rate of about 1 U.S. gallon per minute which wasachieved with a head pressure of 35 to 40 psig.

Of course, apparatus in accordance with the present invention mayincorporate features that are not part of the invention, but which maybe considered desirable. By way of example, FIG. 1 illustrates a portionof a means for sensing the output of ultraviolet lamp 90. This meansincludes a view port 100 leading to a circular wall opening (not shown)through the wall of cylindrical portion 35, a quartz disc 101, athreaded sleeve 102 and an ultraviolet sensor 103. Disc 101 has adiameter larger than the circular wall opening and is held in place overthe opening to provide both a seal against water in chamber 50 and awindow through which energy emitting from lamp 90 can be sensed andmonitored by sensor 103 with known sensing and monitoring circuitry.Such sensing and monitoring circuitry is not shown. However, in thewater treatment system illustrated in FIG. 1, the bulk of such circuitrywould normally be carried in housing assembly 300. Likewise, appropriatepower supply circuitry, both for lamp 90 and for any sensing andmonitoring circuitry, would normally be carried in housing assembly 300.

While the invention has been described in detail in relation toapparatus for treating potable water, it is to be understood that theinvention is not limited to the treatment of water. It may be used totreat other fluids through which ultraviolet energy can permeate in aneffective manner.

Various modifications and changes to the embodiment that has beendescribed can be made without departing from the scope of the presentinvention, and will undoubtedly occur to those skilled in the art. Theinvention is not to be construed as limited to the particular embodimentand should be understood as encompassing all those embodiments that arewithin the spirit and scope of the claims that follow.

What is claimed is:
 1. Apparatus for treating fluid with radiant energy from an ultraviolet lamp, said apparatus comprising: (a) an outer housing comprising first and second ends and an elongated hollow cylindrical portion extending between said ends peripherally around a longitudinal axis of said cylindrical portion; (b) a hollow cylindrical inner housing for housing said lamp, said inner housing being supported by said ends and extending coaxially within said cylindrical portion of said outer housing so as to define an elongated annular chamber between said housing, at least a substantial portion of the length of said inner housing being formed from material sufficiently transmissible to permit ultraviolet energy radiating from said lamp to pass through said inner housing into said chamber and thereby irradiate fluid flowing through said chamber; (c) a fluid inlet conduit extending through said first end from a fluid inlet port to said chamber for receiving said fluid from an external source of fluid and directing said fluid to said chamber; (d) a fluid outlet conduit extending through said second end from said chamber to a fluid outlet port for discharging said fluid from said chamber; and, (e) a single helical shaped input fluid flow guide disposed within said chamber and extending longitudinally therein from said first end for a relatively short distance, said input fluid flow guide for imparting input spiral flow momentum to all of said fluid upon entry to said chamber from said fluid inlet conduit.
 2. Apparatus as defined in claim 1, wherein said guide extends for about one helical revolution within said chamber.
 3. Apparatus for treating fluid with radiant energy from an ultraviolet lamp, said apparatus comprising: (a) an outer housing comprising first and second ends and an elongated hollow cylindrical portion extending between said ends peripherally around a longitudinal axis of said cylindrical portion; (b) a hollow cylindrical inner housing for housing said lamp, said inner housing being supported by said ends and extending coaxially within said cylindrical portion of said outer housing so as to define an elongated annular chamber between said housings, at least a substantial portion of the length of said inner housing being formed from material sufficiently transmissible to permit ultraviolet energy radiating from said lamp to pass through said inner housing into said chamber and thereby irradiate fluid flowing through said chamber; (c) a fluid inlet conduit extending through said first end from a fluid inlet port to said chamber for receiving said fluid from an external source of fluid and directing said fluid to said chamber; (d) a fluid outlet conduit extending through said second end from said chamber to a fluid outlet port for discharging said fluid from said chamber; (e) a helical shaped input fluid flow guide disposed within said chamber and extending longitudinally therein from said first end for a relatively short distance, said input fluid flow guide for imparting input spiral flow momentum to said fluid upon entry to said chamber from said fluid inlet conduit; and, (f) a helical shaped output fluid flow guide disposed within said chamber relatively far from said input fluid flow guide, said output fluid flow guide extending longitudinally within said chamber from said second end for a relatively short distance, said output fluid flow guide for imparting output spiral flow momentum to said fluid as it approaches discharge from said chamber through said fluid outlet conduit.
 4. Apparatus as defined in claim 3, wherein each of said guides extends for about one helical revolution within said chamber.
 5. Apparatus as defined in claim 1, wherein said input fluid flow guide comprises a helical ramp having an inner radius, an outer radius, and a ramp surface extending flatly between said inner radius and said outer radius.
 6. Apparatus as defined in claim 5, wherein the inner radius of said ramp substantially corresponds to an outer radius of said inner housing and the outer radius of said ramp substantially corresponds to an inner radius of said outer housing.
 7. Apparatus as defined in claim 6, wherein said guide extends for about one helical revolution within said chamber.
 8. Apparatus as defined in claim 3, wherein: (a) said input fluid flow guide comprises a first helical ramp characterized by an inner radius of said first helical ramp, an outer radius of said first helical ramp, and a ramp surface of said first helical ramp extending flatly between said inner radius and said outer radius, and; (b) said output fluid flow guide comprises a second helical ramp characterized by an inner radius of said second helical ramp, an outer radius of said second helical ramp, and a ramp surface of said second helical ramp extending flatly between said inner radius and said outer radius.
 9. Apparatus as defined in claim 8, wherein the inner radius of each of said ramps substantially corresponds to an outer radius of said inner housing and the outer radius of each of said ramps substantially corresponds to an inner radius of said outer housing.
 10. Apparatus as defined in claim 9, wherein each of said guides extends for about one helical revolution within said chamber.
 11. Apparatus as defined in any one or more of the foregoing claims wherein said fluid is potable water. 